According to the 12th-century Chronica Polonorum by Wincenty Kadłubek and later retellings by Jan Długosz, Popiel was a prince—sometimes called a king—who ruled over the lands of Gniezno and Kruszwica, in the heart of what would become the Piast realm. Unlike the ideal of a wise and just ruler, Popiel was the embodiment of corruption. He was said to be cruel, decadent, and dismissive of both tradition and the people he governed. His wife, a foreign-born queen, is often depicted as equally ruthless—manipulative, ambitious, and complicit in the worst of his deeds.

The turning point in the legend comes when Popiel poisons his uncles, elder members of the royal family, who had gathered for a feast. They were his advisers, his kin, and—perhaps more dangerously—his critics. With their deaths, Popiel silenced dissent and secured his power. But he had also, as the story goes, invited a supernatural reckoning.

As punishment for this crime, mice—said to have emerged from the remains of the murdered uncles—began to appear in terrifying numbers. At first, they swarmed the royal court. Then, they overran the countryside. No wall or moat could stop them. Popiel and his wife fled, seeking refuge in a tall stone tower by Lake Gopło. But even there, surrounded by water, they were not safe.

The mice came by the thousands. They climbed the tower, breached its walls, and devoured Popiel and his queen alive, leaving behind nothing but bones and silence. The tower, known today as Mysia Wieża (the Mouse Tower) in Kruszwica, still stands—weathered, imposing, and cloaked in legend. Locals say that on quiet nights, you can still hear scratching in the stone.

For centuries, the story of Popiel has been recounted not simply to frighten, but to warn. It is a tale of divine retribution, the consequences of tyranny, and the power of ancestral justice. In this sense, Popiel becomes a kind of anti-king, a figure to contrast with the founders of Poland’s first dynasty—the Piasts—who are portrayed as humble, virtuous, and chosen by the people.

The mice, while fantastical, serve a powerful symbolic function. They represent the unstoppable force of conscience, nature, and fate. In a time before courts and parliaments, legends like this one offered moral order through storytelling. They gave people a framework for understanding justice—if not in this world, then in a higher one.

So, was King Popiel real? Historians largely agree that the story is mythical rather than factual, though it may echo real conflicts from the murky prehistory of the Polish state. The murder of elders, the rise of new dynasties, and the displacement of tribal leadership were all part of the broader evolution of early Slavic societies. Perhaps the tale of Popiel encodes a memory of one such transition—the fall of the old order and the rise of the Piasts.

The Mouse Tower itself, though reconstructed in later centuries, lends a tangible presence to the story. Its location, on the banks of Lake Gopło, and its eerie silhouette have made it a natural setting for legend. Whether or not the events occurred, the power of the story lies in its resonance—its ability to shape identity, spark imagination, and warn against arrogance.

The tale of King Popiel is not just a creepy medieval yarn. It is a story deeply embedded in Poland’s mythic foundation—a reminder of the dangers of unchecked power, the weight of ancestral ties, and the strange, poetic justice of folklore. Through the image of mice overwhelming a stone tower, it whispers a timeless truth: that no ruler, however high, can escape the judgment of history—or the quiet vengeance of the stories told long after they are gone.